The fuel gas used by a conventionally known fuel cell system disclosed, for instance, in JP-A-2004-134272 is hydrogen gas to which an odorant is added. The fuel tank included in the above conventional system stores a mixture of hydrogen and odorant so that the hydrogen can be safely handled. The smell of the odorant can be detected to judge whether a hydrogen line is hermetically sealed.
A catalytic layer is provided in a fuel cell to invoke a power generation reaction. When a gas mixture of hydrogen and odorant is supplied to the fuel cell, the catalytic layer may decrease its responsiveness due to poisoning by the odorant. Therefore, the above conventional system includes an adsorption mechanism, which is positioned between the fuel tank and fuel cell to adsorb the odorant. This ensures that the odorant is removed from the gas mixture of hydrogen and odorant to let the fuel cell generate electrical power in an unobstructed manner.
The adsorption capability of an adsorbent decreases with an increase in the amount of odorant adsorption. To address the above problem, the above conventional system restores the adsorbent's adsorption capability as needed by making use of reductive decomposition by hydrogen. Thus, the conventional technology described above makes it possible to establish a fuel cell system that provides enhanced hydrogen safety while continuously preventing the power generation of the fuel cell from being obstructed by catalyst poisoning.    Patent Document 1: JP-A-2004-134272    Patent Document 2: JP-A-2005-203108    Patent Document 3: JP-A-2004-111167